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Open Access
Management of foot rot of black pepper (Piper nigrum L.) with mycoinoculant enriched vermicompost
(Department of Plant Pathology, College of Agriculture, Vellayani, 2002) Divya, S; Sasikumar Nair
The study, "Management of foot rot of black pepper (Piper nigrum L.) with mycoinoculant enriched vermicompost" was done at the Department of Plant Pathology, College of Agriculture, Veliayani to explore the possibility of using vermicornpost as a carrier material for mass production of biocontrol agents and to test its efficacy in controlling the disease. The talc based inoculum of Trichoderma harzianum and soil based granular inoculum of Glomus Jasciculatum were mass produced in vermicompost either alone or in combination with farmyard manure or neem cake in the ratio 1 : 1 and 5 : 1 respectively and the efficacy was compared with the standard carrier material of FYM + neem cake (10 : 1). The population of T. harzianum 15 DAI was maximum in the treatment combination of VC + NC (5 : 1). However, the influence of these carrier materials on percentage of mycorrhizal infection 50 DAI was not statistically significant. Vermicompost as a carrier material for biocontrol agents was further tested in pepper var. Karimunda inoculated with P. capsici. Carrier materials as such had no significant influence on disease control. Reduction in foliar infection, disease index, stem infection and percentage mortality was observed in treatments with biocontrol agents. Disease control was maximum with the treatments involving T. harzianum while plant growth promotion was maximum with G. Jasciculatum. The physiological changes in pepper plants after inoculation with P. capsici and biocontrol agents were studied. The phenol and OD phenol content was more in pathogen inoculated plants. The defence related enzymes peroxidase, polyphenol oxidase and phenylalanine ammonia lyase were enhanced with pathogen inoculation as well as with the application of biocontrol agents. SDS-PAGE analysis of proteins with samples extracted from plants one day after inoculation of pathogen showed the presence of two novel proteins with molecular . weights of 78 kDa and 28 kDa in diseased samples which were absent in treatments without pathogen and also in plants treated with COC.
Open Access
Management of phytophthora disease of black pepper (piper nigrum L. walp) using plant growth promoting microbial inoculants
(Department of Plant Pathology, College of Agriculture, Mannuthy, 2003) Beena Nair, S; KAU; Anith, K N
The study, "Management of Phytophthora disease of black pepper (Piper nigrum L. Walp) using plant growth promoting microbial inoculants" was conducted at the Department of Plant Pathology, College of Agriculture, Vellayani to investigate the effect of plant growth promoting rhizobacterial strains belonging to fluorescent pseudomonads and Bacillus spp. and the root endophytic fungus, Piriformospora indica on the suppression of nursery wilt of black pepper incited by Phytophthora capsici. Two strains of fluorescent pseudomonads viz., Pseudomonas putida strain 89B61 and P. jluorescens strain RCL3R4, two strains of Bacillus viz., BY -1 and BY -2 and P. indica were included in the study to explore their potential in plant growth promotion and disease suppression. P. capsici inoculated control, uninoculated healthy control, chemical control (0.20 per cent COC drenched at 15 days intervals) and combined application of Trichoderma harzianum and an AMF, Glomus fasciculatum were maintained for comparison. In the dual culture assay, conducted in vitro for preliminary screening, though P. indica exhibited a slight mycelial growth inhibition initially, the pathogen later overgrew the antagonist. Among the bacteria, fluorescent pseudomonad strains exhibited better mycelial growth inhibition 'on both PDA and Carrot Agar. The influence of different biocontrol agents on growth promotion of the black pepper cuttings was not statistically significant. However, the fluorescent pseudomonad, P. putida strain 89B61 exhibited maximum growth promotion. In the experiment conducted to test the potential of vanous plant growth promoting microbial inoculants in suppressing nursery wilt, the plants treated with spore suspension of P. indica exhibited the highest wilt percentage of 93.22 per cent which was more than that in the inoculated control (37.48). The plants treated with the fluorescent pseudomonad, P. jluorescens strain RCL3R4 recorded a wilt percentage of 6.70. All other treatments were highly effective and checked the infection completely. The Bacillus strain, BY -2 exhibited better disease suppression in vivo. The fluorescent pseudomonad, P. putida strain 89B61 also showed disease suppression in vivo, which indicated that it has the dual function of plant growth promotion and disease suppression.
Open Access
Management of bacterial blight of anthurium (anthurium andreanum linden) using botanicals
(Department of Plant Pathology, College of Agriculture, Vellayani, 2002) Sabitha, S R; KAU; Mary, C A
Anthurium (Anthurium andreanum Linden) suffers from a serIOUS disease viz., bacterial blight incited by Xanthomonas axonopodis pv. diefJenbachiae (McCulloch and Pirone) Vauterin et al. A survey was conducted in Thiruvananthapuram district and information on disease intensity and varietal reaction of the disease was studied from randomly selected thirty anthurium gardens. Plants with disease infection upto 50 per cent was noticed in most of the gardens. Generally pink varieties exhibited tolerance while red varieties were susceptible. Both foliar and systemic symptoms were observed. The bacterium was a gram negative, motile, short rod. Potato Sucrose Agar was the best solid medium for growth of the bacterium. Morphological, physiological and biochemical characters of the ten isolates were compared and some characters like nature and rate of growth, virulence and hydrolysis of starch were found varying. Aglaonema sp., Alocasia sanderiana, Anthurium ornatum, Colocasia esculenta, Dieffenbachia spp., Philodendron spp., Syngonium sp. and Xanthosoma sagittaefolium of Araceae family and ornamental plants like Orchid spp., Dracaena spp. Heliconia sp., Sterilitzia reginae and Maranta arundinaceae were hosts of the pathogen. Among the fifteen botanicals tested under in vitro conditions crude extract and 2 : 1 dilution of Allium sativum and Tagetes erecta, crude and two per cent concentration of neem cake extract and one and two per cent neem oil and coconut oil were 'effective in inhibiting the growth of the pathogen. The relative efficacy of five ecofriendly management practices viz., application of A. sativum, T. erecta, neem oil, coconut oil and neem cake extract, at two levels and 100 ppm streptocycline were tested on seven month old tissue culture plants. Pre and post inoculation sprayings with crude extract of neem cake and T. erecta reduced the disease by 85 per cent. When the same spraying schedule with these two botanicals and 100 ppm streptocycline was given on flowering plants, crude extract of neem cake was the most effective followed by crude extract of T. erecta. The effect of streptocycline 100 ppm was on par with T. erecta. The study thus indicates that botanicals could be used as a substitute for antibiotics in the management of bacterial blight of anthurium.
Open Access
Bioherbicidal potential of fungal pathogenes of water hyacinth [Eichhornia crassipes (Mart.) Solms]
(Department of Plant Pathology, College of Agriculture,Vellayani, 2003) Ancy Salim, M; KAU; Naseema, A
The study entitled "Bioherbicidal potential of fungal pathogens of water hyacinth [Eichhornia crassipes (Mart.) Solrns]", was conducted at College of Agriculture, Vellayani, Thiruvananthapuram during 2001-2003. Fourteen pathogenic fungi of water hyacinth obtained from the survey conducted as a part of the DST project on "Biocontro l of water hyacinth using mycoherbicides" were used for the study. Fungi which were not identified earlier were characterized and identified based on the cultural and morphological characters and was confirmed by sending to Agharkar Research Institute, Pune. These three fungi viz., Bipolaris tetramera, Drechslera sp. and Pestalotiopsis guepinii, were new records on water hyacinth. The fungi varied in the symptom development on water hyacinth with respect to nature of symptoms, parts affected and the time taken for the symptom development. The intensity of infection by the fungi varied from 9.94 to 58.80 per cent. Only five fungi viz., A.eichhorniae, F. moniliforme, F. oxysporum (isolate 2), F. pallidoroseum (isolate 3) and I M. advena gave more than 45 per cent intensity of infection. Cell free metabolites of the various fungi also varied in the symptom development. Intensity of damage varied from 8.03 to 89.00 per cent. Maximum was recorded by M. advena followed by F. pallidoroseum (49.80 per cent), A. eichhorniae (48.80 per cent) and F. oxysporum (47.20 per cent). Host range of A. eichhorniae, F. moniliforme and F. oxysporum was studied in detail. A. eichhorniae infected only three weed plants out of the 37 cultivated and 39 weed plants tested. F. moniliforme infected five 11 cultivated and 11 weed plants. F. oxysporum was found to be pathogenic to seven cultivated and nine weed plants. Combined application of A. eichhorniae and F. p allidorose um recorded higher intensity of infection than when sprayed alone. A. eichhorniae was found to give effective destruction of the weed at 107 spores per ml concentration. A. eichhorniae at 107 spores per ml and F. p all idoroseum at lOll spores per ml together recorded more intensity of infection of 89.84 per cent than when sprayed alone. Talc based combination product of A. eichhorniae and F. pallidoroseum when sprayed at 10.00 per cent concentration recorded an intensity of infection of 93.20 per cent, 10 days after spraying. The formulated product could retain the viability of spores of the pathogens at room temperature for 15 days.
Open Access
Biocontrol of bacterial wilt in tomato using arbuscular myaorrhizal fungi
(Department of Plant Pathology, College of Horticulture, Vellanikkara, 2003) Nandakumar, A; KAU; Surendra Gopal, K
The studies on "Biocontrol of bacterial wilt in tomato using arbuscular mycorrhizal fungi" were carried out at the Oept. of Plant Pathology, College of Horticulture, Vellanikkara during the period 2000 - 2002. The main objectives of the study were to identify suitable native AMF from high and low wilt incidence areas of Thrissur and Palakkad districts, screen them against Ralstonia solanacearum in pot culture under sterile and wilt sick conditions, to determine the optimum inoculation time and inoculum density of :\\1f and to test ~h,- ,,;;;cicncy 0: Aj,\1f in thc wilt sick field. The soil samples collected from Thrissur and Palakkad district were analyzed for their nutrient status, pH, Ralstonia population and total AMF spore count. The Vellanikkara soils were acidic with low ,K, Ca and Mg and high P content when compared to Ozhalapathy and Eruthiampathy soils. The Ralstonia population were generally higher in Vellanikkara soils. On the other hand, Ozhalapathy soils had higher AMF spore count. The Glomus sp. was found to be the most predominant AMF in the soils of high wilt (Vellanikkara, Thrissur district) and low wilt incidence (Ozhalapathy and Eruthiampathy, Palakkad district). The screening of the predominant native AMF cultures against R. solanacearum were carried out individually and in combinations under sterile conditions along with the TNAU commercial culture [or comparison. The treatments with the native AMF combinations 1'i2., GIOIllIlS sp. (OT) + Glomus sp. (ER), Glomus sp. (OT) + Glomus sp. (VM) and Glomus sp (OM) - Glomus sp. (VBT) recorded the least percent wilt incidence with the native A0.1F combination Glomus sp. (OM) + Glomus sp. (VBT) recording the maximum number of days of plant survival (11 days). The dry weight and root length were also higher for these three native AM F combinations. The determination of the optimum inoculation time (at the time of sowing, at 15 days before transplanting and at the time of transplanting) in combination with the inoculum density (@ 25 g kg 1 soil, 50 g kg 1 soil and 75 g kg -I soil) were carried out using different species of AMF in pot culture using wilt sick soil. The inoculation time at 15 days before transplanting 75 g kg -I soil was found to be optimum. This was evaluated further, under pot culture and field experiment studies using the native AMF combinations selected from the screening experiment. The selected native AMF combinations from the screening experiment were tried at 15 days before transplanting @ 75 g kg -I soil in pot culture using wilt sick soil in comparison with the TNAU commercial culture to select the best two combinations for the field experiment. The native AMF combinations recorded the least percent wilt incidence and maximum number of days of plant survival when compared to the TNAU commercial culture. The AMF combinations Glomus sp. (OM) + Glomus sp. (VBT) and Glomus sp. (OT) + Glomus sp. (VM) were found to be the best. A field experiment to test the efficacy of the selected native AMF culture combinations were carried out using the tomato varieties Pusa Ruby (susceptible) and Mukthi (moderately resistant). The native AMF combination Glomus sp. (OT) + Glomus sp. (VM) recorded maximum number of days of plant survival (32 and 50 days respectively) in both the tomato varieties. However, it could not prevent wilt incidence in the case of Pusa Ruby variety, which recorded 100 percent wilt, and Mukthi variety 97 .. 9 % wilt incidence. The same native AMF combinations Glomus sp. (OT) + Glomus sp. (VM) also recorded maximum fruit number in Mukthi whereas Pusa Ruby did not produce fruits as they did not survive even upto flowering. The present study clearly indicated that the native AMF combination Glomus sp. (OT) + Glomus sp. (VM) was the best in pot culture studies using wilt sick soil and could delay the disease incidence in the susceptible Pusa Ruby variety of tomato upto 82 days after transplanting. However, under field conditions it could delay the disease incidence in the susceptible variety Pusa Ruby only upto 32 days and in the moderately resistant variety Mukthi upto 50 days. So more extensive studies are needed to develop a suitable native AMF to control the bacterial wilt in tomato which is effective under field conditions.
Open Access
Utilization of fungi for composting and mushroom production on coirpith
(Department of Plant Pathology, College of Agriculture, Vellayani, 2003) Sherin Salam, A; KAU; Geetha, D
The present study entitled "Utilization of fungi for composting and mushroom production on coirpith" was conducted during 2001 to 2003 at College of Agriculture, Vellayani, Thiruvananthapuram district with the objective to isolate most efficient fungi for degradation of coirpith and standardization of technology for mushroom production on coirpith. Four lignocellulolytic fungi viz., Aspergillus niger, A. ochraceous, Trichoderma harzianum and Rhizopus stolonifer were isolated from retted coirpith. Three mushrooms viz., Pycnoporus sanguine us, Ganoderma applanatum and Pleurotus tuber-regium collected during surveys conducted in different parts of Thiruvananthapuram district, and Lentinus edodes, Pleurotus florida and Calocybe indica were procured from TNAU and College of Agriculture, Vellayani. P. tuber-regium, a mushroom collected during the study is a new report from India. This edible mushroom has a biological efficiency of 46 per cent and is ideally suited for cultivation in Kerala. T. harzianum was the fastest colonizer on retted coirpith followed by G. applanatum and L. edodes. The maximum reduction of organic carbon, C:N ratio, cellulose and lignin and the maximum increase of nitrogen content in retted coirpith was recorded when it was degraded by T. harzianum, Among the different substrates used for mushroom production, the maximum yield of P. florida was realized in a substrate containing 1: 1 combination of retted coirpith and spent mushroom substrate while the maximum yield of C. indica was observed in a substrate containing 1:3 combination of non-retted coirpith and paddy straw. , Composted coirpith was found to be unsuitable as a substrate for large scale cultivation of oyster and milky mushrooms.
Open Access
Integrated management of leaf rot of coconut
(Department of Plant Pathology, College of Agriculture, Vellayani, 2002) Vrinda, T S; Joseph, P J
The study entitled as "Integrated management of leaf rot of coconut" w as conducted at the Department of Plant Pathology, Co l.cge of Agr iculturc. Ve l l a van i and Iie ld trial was conducted at RARS. Kumarakorn. Extensive iso lai io n s. pathogenicity and characterization studies of the pathogens assoc i aic d with leaf rot infected spindle leaf of coconut from di ffercnt r e g ions 0 I' f ve southern districts of Kerala revealed that Collct otrichu m g/oco.,porioidcs. Fusarium so/ani, Fusarium. monil if..rniae, Fusari utn oxvsp or utn, Cephalosporium sacchari. Exserohilum rostrat um. Gl iocl adi um roselllll.<';C\!o!idillll7 sp. and Curv ular i a sp. played ct io lo gj 0" LRD. Based on frequency 01' isolarions. Fusarium spp. .ind C .g/()(;o.,porioides Viere identified as major pathogens or LRD in these areas. The present study constitutes the first report or the ct io log ica l ro l c of Scvt ul uliurn ::;0 in leaf rot incidence. Symptomatology of the disease based on natural incidence in the I'dd and upon artificial inoculation were clearly described The in vit ro interactions of different dual combinations of LRD pathogens were found to be predominantly associative rather than inhibitory in nature. The rapid lesion development of certain dual combinations of the pathogens upon artificial inoculation further signified the associative nature of these pathogens. Extensive in vi/m screening and leaf bit assay of different antagonistic microorganism identified T9 culture of Trichoderma sp. PSI culture of Pse u domonasfluorescens as two potential agents against i he major pathogens of LRD. The in vitro interactions study of the selected fungal and bacterial antagonist showed that both are incompatible and hence unsuitable for combined delivery. Bioassay results showed that fungicides hcxaconazo lc and propiconazole completely inhibited the growth of C. gloeosporioides. E. rostra/um and F. solani while mancozeb was more effective at higher concentrations. one of the fungicides was inhibitory to P. j7uorescens while Trichoderma sp. was inhibited by hex aconazo!e and hence the fungal antagonist was unsuitable for combined delivery with the fungicides. Evaluation of different components of disease management indicated that phytosanitation coupled with hexaconazole application was effective in reducing disease severity of leaf rot in the field.
Open Access
Management Of Bacterial wilt Of Solanaceous Vegetabbles Using Microbial Antagonists
(Department of Plant Pathology, College of Horticulture,Vellanikkara, 2003) Manimala, R; KAU; Sally Mathew, K
Studies on 'Management of bacterial wilt of solanaceous vegetables using microbial antagonists' was conducted at the College of Horticulture, Vellanikkara during 2000- 2002. The major objective was to find out effective microbial antagonists against bacterial wilt ofbrinjal, chilli and tomato. Estimation of population of R. solanacearum showed the maximum in Vellanikkara than Ozhalapathy. The total rnicroflora was higher in Ozhalapathy than Vellanikkara and resistant varieties of the three crops recorded better association of microflora than susceptible ones. In in vitro evaluation , rhizosphere organisms isolated from the low wilt incidence area (Ozhalapathy) exhibited better antagonism against R. solanacearttm than those isolated from Vellanikkara. Among them, fungi were more effective than bacterial and actinomycete antagonists. The major fungal antagonists belonged to Trichoderma spp. and Aspergillus spp. T. viride (Ozhalapathy), T. pseudokoningii (forest soil) and Aspergillus niger (Eruthyampathy) were the most effective ones against R. solanacearum. Among the bacterial antagonists, P. aeruginosa and B. subtilis (Vellanikkara) were promising one. All commercial antagonists viz. T. viride, A. niger (Varanasi), A. niger (AN 27) T. harziamtm, B. subtilis and P. fluorescens were also effective against R. solanaeearum. Of the culture filtrates tested, T. virens and.E. subtilis (commercial) showed the maximum inhibition of the pathogen. The antagonists which were found most effective in laboratory condition performed well in pot culture studies also. Among the different methods of application of antagonists adopted, either seed treatment + soil drenching or root dipping were effective in reducing the wilt incidence and in delaying the wilt appearance. Use of antagonists in highly susceptible varieties did not give a promising control of bacterial wilt under field condition. In field trial, using a moderately resistant variety Mukthi, antagonists showed some effect in controlling bacterial wilt indicating that, an integrated effect by combined use of host resistance and microbial antagonists can provide a better control of bacterial wilt pathogen in the field.
Open Access
Effect of nitrogen, phosphorus and potassium nutrition on incidence and intensity of grey blight of coconut
(Department of Plant Pathology, College of Agriculture, Vellayani, 2003) Subramanyan, K; KAU; AdvisorSantha Kumari, P
The investigation on the "Effect of nitrogen, phosphorus and potassium on incidence and intensity of grey blight of coconut" was conducted during 2001-2002 at the Coconut Research Station, Balararnapuram, Thiruvananthapurarn, Kerala. The coconut palms cultivated in the Permanent Manurial Trial experimental plot of the station was used for the studies. The pathogen was isolated from the infected leaf tissue by the standard tissue isolation technique. Cultural and morphological studies confirmed the identify of the pathogen as Pestalotiopsis palmarum (Cooke) Stey. Among the different artificial media tried potato dextrose and sucrose were the best for growth and sporulation of the pathogen. Conidial morphology of fungus was studied on six media. The fungus produced largest conidia and appendages on PDA and PSA, while those produced on PDA had the maximum breadth. The maximum incidence and intensity of grey blight was observed in the month of August. During the subsequent months it declined and the least was observed in February . . The incidence and intensity of the disease was correlated with different levels of NPK fertilizer application and nutrition status of palms. Higher rate of nitrogen, phosphorus and potash application in soil resulted in higher rate of these nutrients in the leaf samples and higher rate of the disease. The disease intensity was maximum In palms supplied with the treatment combination N )P2K2 and minimum in N2P2Ko. The highest disease incidence and intensity were observed when the relative humidity was above 83 per cent. The maximum temperature at this period was 29.7oC and the minimum temperature 20.7()C. The rainfall during this period was 243.3 mm. These weather parameters were observed during the month of August. The lowest disease incidence and intensity was observed when the relative humidity was 77.2 per cent. The maximum temperature was 31.4°C and minimum temperature 22.3°C. Rainfall during this period was 15 mm. These weather parameters were recorded during the month of February. There was a positive correlation on the incidence and intensity of grey blight with rainfall, relative humidity and wind speed where as a negative correlation was observed with temperature. Nutrient composition of the healthy leaf tissue indicated that with an increase in the nitrogen level, there was a corresponding increase in the nutrient status of major, secondary and micronutrients. A similar trend was noticed with phosphorus and potassium also. However, with increase in potassium level there was a corresponding decrease in the magnesium content. Similarly with an increase in phosphorus a decrease in zinc and boron content was observed both in healthy and diseased leaf tissues. Both in two way and three way interactions, involving NP, NK, PK and NPK the composition of nutrients of healthy as well as in diseased leaves increased with increase in the levels of nitrogen, phosphorus and potassium. Chlorophyll, total sugar, amino acid and phenol contents in healthy tissues were found to be high with higher levels of fertilizer application.

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